1. Field of the Invention
This invention relates to a hydrostatic pump with a variable delivery volume which can be operated in a closed circuit and is driven by a drive engine, in particular, by an internal combustion engine. To control the delivery of the pump, a control device is provided which can be actuated as a function of a control pressure, which is a function of the speed of the drive engine.
2. Technical Considerations
Hydrostatic pumps of this general type with variable displacement volumes which are operated in a closed circuit can be used, for example, as pumps in traction drives of mobile work machines.
As a result of the control of the pump displacement as a function of the speed of the drive engine that drives the pump, such as an internal combustion engine, an automotive control system is achieved in which the pump pivots as a function of the speed of the drive engine so that on a hydrostatic traction drive, the speed of travel of the mobile work machine increases with the increasing speed of rotation of the drive engine.
A pump of the known art with an automotive control system of this type is described in DE 28 23 559 A1.
With an automotive control of a traction drive of this type, to achieve different speeds of travel at any desired speed of the drive engine, the operator actuates an “inch pedal”. When the inch pedal is actuated, the pump is actuated to reduce the displacement. As a result, the speed of travel at the specified engine speed is reduced.
The actuation of two pedals, namely, a gas pedal and an inch pedal, however, requires complex operation and undue effort on the part of an operator. In particular, it requires great skill to precisely actuate a traction drive with an automotive control system.
Therefore, it is an object of the invention to provide a pump of this general type but which is provided with improved control characteristics.